The synthesis and characterization of fluorinated polyimides derived from 2′-methyl-1,4-bis-(4-amino-2-trifluoromethylphenoxy)benzene and various aromatic dianhydrides

The synthesis and characterization of pendant methyl fluorinated polyimides (5a–f) derived from fluorinated diamine monomer, 2′-methyl-1,4-bis(4-amino-2-trifluoromethylphenoxy)benzene (2) and several aromatic dianhydrides (3a–f) is described. The synthesis of new fluorinated diamine (2) and the precursor fluorinated dinitro compound (1 Sroog, C. E. Polyimides. Prog. Polym. Sci. 1991, 16, 561–694. DOI: 10.1016/0079-6700(91)90010-I.[Crossref], [Web of Science ®] , [Google Scholar]) are also discussed. The presence of trifluoromethyl group in the backbone of the fluorinated polyimide exhibited better optical transparency, organic solubility, dielectric constant, moisture adsorption and maintained mechanical and thermal properties than trifluoromethyl-free analogs (5′a–f). The highly fluorinated polyimides 5f via chemical imidization exhibited the best organic solubility, highest optical properties (b* cutoff wavelength = 367 nm). In addition, the highly fluorinated polyimide via thermal imidization also displayed relative lower dielectric constants (3.06 at 1 MHz) and moisture adsorption (0.16%) than most fluorinated polyimides. The t-butyl and phenyl substituted fluorinate diamine analogs and their fluorinated polyimides were also compared and discussed on thermal and mechanical properties.